This invention relates to a method of detecting an interference in an apparatus such as a machining tool or robot which performs the asynchronous control of a plurality of mechanical systems.
FIGS. 1 and 2 are explanatory diagrams for a description of an interference simulation in a multiple spindle lathe having two machining systems. More specifically, FIG. 1 shows the case where it is determined through interference simulation that no interference occurs, and FIG. 2 shows the case where it is determined through interference simulation that an interference may occur. In FIGS. 1 and 2, reference characters 1a and 1b designate workpieces in first and second mechanical systems, respectively; 2a and 2b, tools (cutting tools) of the first and second mechanical systems, respectively; and 3a and 3b, the chucks of the first and second mechanical systems, respectively.
As was described above, FIGS. 1 and 2 shows the results of simulation of the control operations of the conventional multiple spindle lathe; that is, the positions of the workpieces, tools, and chucks of the two mechanical systems at a certain time instant As the simulation of the control operation advances, these figures are dynamically (or in a motion simulation mode) moved, so that their positions changing with time are simulated. When their figures are as indicated in FIG. 6 during the simulation, the operator can detect that the workpiece 1a of the first mechanical system and the workpiece 1b of the second mechanical system interfere mechanically with each other as indicated at A in FIG. 2. That is, it is necessary to amend the machining program. Therefore, in response to the indication of the interference of the workpieces, the operator corrects the machining program, and after confirming through simulation that no interference is caused, he starts the actual machining operation. Thus, the interference of workpieces can be avoided in the actual machining operation.
As is apparent from the above description, the conventional simulation is based on the complete reproduction of the actual machining operation. However, in a computerized numerical control lathe or the like, generally its plurality of mechanical systems are controlled in an asynchronous manner. Because of the automatic control of the machining speed in the actual machining operation (the feed speed being automatically controlled on the machining load), there occur errors between the simulation and the actual machining operation; that is, it is impossible to completely simulate the machining operation.